Quantitative assessment of human immunodeficiency virus type 1 replication in human xenografts of acutely infected Hu-PBL-SCID mice

Replication of the IIIB strain of human immunodeficiency virus type 1 (HIV-1IIIB) in CB.17 scid/scid mice reconstituted with human peripheral blood lymphocytes (Hu-PBL-SCID) was investigated. Hu-PBL-SCID mice could be infected, in a dose-dependent manner, when HIV-1IIIB was injected intraperitoneally. Replication-competent HIV-1 could be recovered from spleen, peripheral blood, bone marrow, thymus, lymph node, and peritoneal cavity, indicating the ability of the infection to spread to human tissue throughout the chimeric animals. HIV-1 infection was quantitated using p24 determination, end-point dilution culture, and polymerase chain reaction amplification. The level of HIV-1 replication in Hu-PBL-SCID mice was found to approximate the level reported in human infection. No HIV-1-specific immune response was generated to this infection, but nonspecific immune activation did occur, as also reported in human infection. Similarities therefore exist between HIV-1 infection of humans and Hu-PBL-SCID mice, which makes the latter an in vivo model in which to study HIV-1 replication.

Comparison of digestibility, nutritive value, and storage characteristics of different forms of cottonseed in diets fed to lactating dairy cows

Thirty-two Holstein cows averaging 70 d postpartum were used to compare digestibility of whole short staple cottonseed (SS) to whole Pima (WP), coarsely cracked Pima (CrP), and ground Pima (GP) cottonseeds and their effects on lactational performance. Cottonseed was fed at 15% of diet DM. Milk and solids-corrected milk (SCM) yields were higher for cows fed GP than for cows fed CrP or WP but were not different from yields of cows fed SS. Feed efficiency (SCM/DMI) was higher for cows fed GP and SS than for those fed WP. Milk of cows fed GP was lower in stearic acid but higher in linoleic and linolenic acids than milk of cows fed SS. Whole seeds passing into the feces (percentage of consumed) were higher for WP (12.3%) than for SS (6.2%). Total tract digestibility of ether extract was lower for WP than for other diets. Digestibilities of other nutrients were not different. To test storage characteristics, samples of cottonseed were incubated at 32 degrees C and 30% relative humidity for 0, 10, 20, and 30 d, or stored at ambient temperatures in covered buckets for 9 mo. No differences in amount of free fatty acids between incubated samples were noted, and only CrP stored in buckets for 9 mo was significantly higher in free fatty acids than initial or frozen seed. No differences in aflatoxin were detected, and levels were very low. Milk yield of cows fed GP diets was similar to that of cows fed SS diets and slightly higher than those of cows fed CrP or WP diets. Processing the Pima seed increased feed efficiency.

Performance of dairy cows fed short staple, Pima, and cracked Pima cottonseed and feed characteristics

Compared with short staple cottonseed, Pima cottonseed was higher in CP, ether extract, and oleic acid and lower in NDF, ADF, and linoleic acid. Pima cottonseed had greater bulk density, but short staple cottonseed had stronger seed coat strength; Pima cottonseed contained more of the (-)-gossypol isomer than short staple cottonseed. Lactating Holstein cows were fed whole short staple cottonseed, whole Pima cottonseed, and cracked Pima cottonseed at 15% of dietary DM for 70 d after a pretrial covariate period. The DMI was not significantly different among treatments, but cows fed whole Pima tended to yield less milk than those fed short staple and less FCM than those fed cracked Pima. Feed efficiency was improved by processing Pima cottonseed. Milk fat content was higher for whole and cracked Pima than for short staple cottonseed; gross feed efficiency was greatest for cows fed cracked Pima cottonseed. Whole cottonseed in feces was highest for whole Pima, intermediate for short staple, and negligible for cracked Pima cottonseed. Concentrations of milk stearic acid were lower, and linoleic acid higher, for cows fed cracked Pima than for cows fed short staple cottonseed. Total tract digestibility of ADF was least on the cracked Pima cottonseed diet, and ether extract digestibility was higher on cracked than on whole Pima cottonseed diets.

IL-2 independent growth and cytotoxicity of herpesvirus saimiri-infected human CD8 cells and involvement of two open reading frame sequences of the virus

Herpesvirus saimiri is a primate tumor virus and induces acute T cell lymphomas and leukemias in New World monkeys and rabbits. We show in this report that infection of human peripheral white blood cells with a group C strain 484-77 results in selective expansion of CD8 lymphocytes with strong cytotoxic activity and these cells do not require interleukin-2 (IL-2) for growth. Infected cell cultures, termed herpesvirus-activated killer (HAK) cells, have been continuously maintained for several months in tissue culture and these HAK cells contain multiple copies of stable circular viral episomes. The growth and cytotoxicity of HAK cells was found independent of IL-2. Analysis of deletion mutant infected cells suggests that at least two open reading frame sequences of a bicistronic mRNA encoded by the viral genome is involved in controlling IL-2 independence. This model could facilitate studies on growth regulation of human cytotoxic T cells that are important effector cells in immune responses against infectious diseases and cancer and should help us to elucidate the mechanism of transformation by H. saimiri oncogenes.

Human peripheral blood xenografts in the SCID mouse: characterization of immunologic reconstitution

Immune reconstitutions (hu-PBL-SCID mice) resulting from adoptive transfer of human peripheral blood mononuclear cells into 1800 C.B-17 scid-/scid-mice were characterized. Over 90% of reconstitutions were successful as evidenced by human immunoglobulin production. Variability was noted with donor, cell number, and cell type. Human cells (T lymphocytes, few B cells) could be recovered by 5 days after engraftment. High levels of soluble CD8 and interleukin-2 receptors were detected in sera of hu-PBL-SCID mice. Cells recovered from 17 mice proliferated in response to antigens to which the donor had been primed; responses to nonboosted antigen also increased in some animals. After reconstitution, lymphocytes were found in the spleen and lymph nodes without full restoration of normal architecture. The hu-PBL-SCID mouse shows promise as a model system for a variety of immunologic studies. The inherent variation in the system must be minimized for appropriate use of the model.

Nevirapine synergistically inhibits HIV-1 replication in combination with zidovudine, interferon or CD4 immunoadhesin

OBJECTIVE

To determine whether synergistic inhibition of HIV-1 replication would result from the in vitro use of nevirapine in combination with zidovudine, interferon (IFN)-alpha 2C, and CD4 immunoadhesin.

DESIGN AND METHODS

The non-nucleoside reverse transcriptase inhibitor nevirapine (formerly BI-RG-587) was tested in combination with the other antiretrovial agents. Assays were performed on stimulated peripheral blood lymphocytes infected with HIV-1. Virus replication was assessed by the release of viral p24 antigen into culture supernatants. The median-effect principle was used to assess for synergistic interactions of the combined agents.

RESULTS

Zidovudine, IFN-alpha 2C and CD4 immunoadhesin, when used in combination with nevirapine, synergistically inhibited HIV-1 replication in human peripheral blood lymphocytes compared with each agent used alone. Some analyses were also consistent with additive effects, but antagonism was not noted.

CONCLUSION

These in vitro findings provide a scientific basis for future trials with similar drug combinations.

Early viremia and immune responses in vertical human immunodeficiency virus type 1 infection

Thirty-three infants born to human immunodeficiency virus type 1 (HIV-1)-seropositive women were evaluated from birth using plasma and peripheral blood mononuclear cell (PBMC) cultures, polymerase chain reaction, and serum p24 antigen assays. Five children were identified as infected. Evidence of infection was found in cord blood and subsequent samples from 2 infected children, suggesting in utero infection. Virologic studies on cord blood and early neonatal specimens from the 3 other infected children were negative but became positive by 8 weeks of age, suggesting either intrapartum transmission or sequestration of virus with subsequent detection. An increase in blood (plasma and PBMC) virus titers consistent with primary viremia was observed in 4 infants between 3 and 16 weeks of age. Blood virus titers subsequently declined in the absence of antiretroviral therapy and in the absence of activated HIV-1-specific cytotoxic T lymphocyte responses or broadly neutralizing antibodies. Confirmation of these results in larger studies may be helpful in the design of clinical trials to interrupt vertical transmission or to modify the course of infection.

Effect of protein quality and evaporative cooling on lactational performance of Holstein cows in hot weather

Twenty-four Holstein cows in midlactation during summer in southern Arizona were fed diets supplemented with a combination of blood, fish, and soybean meals (high quality protein) or corn gluten meal (low quality protein). Diets were balanced for CP content and estimated ruminal protein degradability, but they differed in Lys concentration (.98 vs. .59% of DM). Milk yield for the 56-d trial was higher by 11% for cows fed high than for cows fed low quality protein and higher by 9% for cows receiving evaporative cooling plus shade than for cows receiving shade alone. Milk fat and protein yields also were greater for high than for low quality protein and for evaporatively cooled plus shade than for shade treatments. Intake of DM tended to be higher for cooled cows but was unaffected by protein source. Cooled cows had lower rectal temperatures (38.6 vs. 39.1 degrees C) and respiration rates (64 vs. 82/min) than noncooled cows. Interactions between protein quality and cooling method were not statistically significant; however, cooled cows fed high quality protein had higher milk yield than noncooled cows. Digestibility of DM was higher for the low than for the high quality diet, but CP digestibilities were not different. Cows fed supplemental protein of higher Lys content were more productive.

Pharmacokinetics of nevirapine: initial single-rising-dose study in humans

Nevirapine, a nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase, was administered for the first time to humans in a pilot study designed to investigate the pharmacokinetics and tolerance of the drug following single-dose administration to 21 HIV-1-infected individuals. The study followed a parallel design. Different groups of three subjects each were given one of seven dose levels (2.5 to 400 mg) in sequential order, starting with the lowest dose. Each subject received only one dose. Nevirapine was rapidly absorbed at all doses from a tablet formulation. Peak concentrations in plasma were generally achieved within 90 min of dose administration. Secondary peaks were also noted between 3 and 12 h or between 24 and 28 h, the latter being noted mainly in subjects receiving the higher doses. After 24 h, concentrations in plasma declined in a log-linear fashion. The terminal half-life and mean residence time exceeded 24 h in all but one subject, indicating a prolonged disposition time in this population. Both peak concentrations in plasma and areas under the plasma concentration-time curves increased proportionally with increasing dose from 2.5 to 200 mg; however, the increase in the peak concentration in plasma and the area under the plasma concentration-time curve appeared to be less than proportional at the 400-mg dose level in this small number of subjects. This observation may be due to increased clearance or decreased absorption at the highest dose or population differences in absorption or clearance between doses. Studies with a cross-over design are planned to resolve these issues. The pharmacokinetic characteristics of nevirapine are appropriate for once-daily administration. A daily 12.5-mg dose is predicted to achieve trough concentrations in plasma in the range required to totally inhibit replication of wild-type HIV-1 in human T-cell culture.

Relationship between platelet monoamine oxidase B activity and alleles at the MAOB locus

Genetic variations in monoamine oxidase (MAO)-B activity have been proposed to have a contributory role in several neurologic and psychiatric diseases. Variations in activity could affect rates of degradation of exogenous amines, including toxins, precursors of toxins (like 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), or false transmitters, and of endogenous amines, such as neurotransmitters. In this study a highly polymorphic (GT)n repeat element was used to mark alleles at the MAOB locus. The MAOB allele status and levels of platelet MAO-B activity were determined for 41 control males. No correlation was noted between specific alleles and levels of MAO-B activity in this sample set. This suggests that the structural gene for MAOB is not usually the primary determinant of activity levels in platelets.

Diagnosis of vertical human immunodeficiency virus type 1 infection by whole blood culture

The qualitative and quantitative performance of a human immunodeficiency virus type 1 (HIV-1) whole blood culture method was assessed for use in the diagnosis of vertical HIV-1 infection. This method requires < 1 mL of whole blood and allows for the quantification of blood virus load. HIV-1 was isolated from 36 (95%) of 38 whole blood specimens from 27 HIV-1-infected children compared with 0 of 16 whole blood specimens from 16 uninfected children. HIV-1 titers were significantly higher in severely symptomatic children (2450 TCID/mL) than in less symptomatic children (179 TCID/mL). This simple quantitative culture assay may be useful for the early diagnosis of vertical HIV-1 infection, the assessment of blood virus load, and the evaluation of antiretroviral therapies.